DOC AIRBUS | AMM A320FENGINE FIRE AND OVERHEAT DETECTION - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
A fire can be due to excessive overheat or flammable fluid leaks and can endanger the aircraft safety.
Thermo-sensitive elements detect fire or overheat conditions. They trigger the fire warnings by means of the Fire Detection Unit (FDU) when the temperature reaches the threshold of the monitored area of the engine.
The ENG/APU FIRE panel (1WD) includes the controls, indications and a test function for each engine.
In the section of this panel related to the engine fire detection, two functions are available:
** ON A/C NOT FOR ALL A fire can be due to excessive overheat or flammable fluid leaks and can endanger the aircraft safety.
Thermo-sensitive elements detect fire or overheat conditions. They trigger the fire warnings by means of the Fire Detection Unit (FDU) when the temperature reaches the threshold of the monitored area of the engine.
The ENG/APU FIRE panel (1WD) includes the controls, indications and a test function for each engine.
In the section of this panel related to the engine fire detection, two functions are available:
- a FIRE warning which comes on red on the ENG 1(2) FIRE pushbutton switch after a positive fire detection,
- a manual test capability of the system.
- two fire detection loops installed in parallel in the fire zones and connected to a Fire Detection Unit (FDU). Each fire detection loop comprises three detectors connected in parallel,
- one FDU per engine, which processes signals from the detectors,
- an ENG/APU FIRE panel on the overhead panel with per engine:
. one ENG FIRE pushbutton switch,
. one TEST pushbutton switch, - associated warnings and indications.
NOTE: For APU see ATA chapter 26-13-00.
2. Component Location
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ENG/APU FIRE Panel (20VU) and Fire Detection Unit (FDU) - Component Location| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||||
| 1WD | ENG/APU FIRE PNL | 210 | 26-12-12 | ||
| 2WD1 | FDU-ENG1 | 126 | 26-12-34 | ||
| 2WD2 | FDU-ENG2 | 126 | 26-12-34 | ||
| ** ON A/C NOT FOR ALL | |||||
| 3WD1 | DET-FIRE, ENG 1 PYLON LOOP A | 437AL | 415 | 26-12-16 | |
| 3WD2 | DET-FIRE, ENG 2 PYLON LOOP A | 447AL | 425 | 26-12-16 | |
| ** ON A/C NOT FOR ALL | |||||
| 3WD1 | DET-FIRE, ENG 1 PYLON LOOP A | 415 | 26-12-16 | ||
| 3WD2 | DET-FIRE, ENG 2 PYLON LOOP A | 425 | 26-12-16 | ||
| ** ON A/C NOT FOR ALL | |||||
| 4WD1 | DET-FIRE, ENG 1 PYLON LOOP B | 437AL | 415 | 26-12-16 | |
| 4WD2 | DET-FIRE, ENG 2 PYLON LOOP B | 447AL | 425 | 26-12-16 | |
| ** ON A/C NOT FOR ALL | |||||
| 4WD1 | DET-FIRE, ENG 1 PYLON LOOP B | 415 | 26-12-16 | ||
| 4WD2 | DET-FIRE, ENG 2 PYLON LOOP B | 425 | 26-12-16 | ||
| ** ON A/C NOT FOR ALL | |||||
| 4000WD1 | DET-FIRE, FAN LOOP A | 430 | 26-12-15 | ||
| 4000WD2 | DET-FIRE, FAN LOOP B | 430 | 26-12-15 | ||
| 4001WD1 | DET-FIRE, CORE LOOP A | 430 | 26-12-17 | ||
| 4001WD2 | DET-FIRE, CORE LOOP B | 430 | 26-12-17 | ||
3. System Description
The fire detection system is of the electro-pneumatic type. On each engine, there are two continuous loops for the fire detection.
The loops are connected in parallel to a Fire Detection Unit (FDU). The connection is made through an AND logic to avoid spurious FIRE warnings.
In case of failure of one loop, the AND logic becomes an OR logic. The aircraft can be released in this configuration.
The fire detection loops are monitored by the FDU. The monitoring device indicates the loss of a fire detection loop to the crew members (Flight Warning System).
For one engine, each loop:
** ON A/C NOT FOR ALL The fire detection system is of the electro-pneumatic type. On each engine, there are two continuous loops for the fire detection.
The loops are connected in parallel to a Fire Detection Unit (FDU). The connection is made through an AND logic to avoid spurious FIRE warnings.
In case of failure of one loop, the AND logic becomes an OR logic. The aircraft can be released in this configuration.
The fire detection loops are monitored by the FDU. The monitoring device indicates the loss of a fire detection loop to the crew members (Flight Warning System).
For one engine, each loop:
- comprises three fire detectors connected in parallel. The detectors are installed in the nacelle and pylon fire zones.
- is connected to a separate channel of the FDU
- is connected through the related channel, to four of the eight lamps in a red warning light common to the two loops. This warning light is integral with the ENG 1(2) FIRE pushbutton switch located on the ENG/APU FIRE panel (overhead panel).
The fire detection system can be tested using the TEST pushbutton switch on the ENG/APU FIRE panel.
4. Power Supply
The engine fire and overheat detection system gets the electrical power from the DC system of the aircraft.
The engine fire and overheat detection system gets the electrical power from the DC system of the aircraft.
A. Circuit Breakers
The system is supplied through these circuit breakers:
The system is supplied through these circuit breakers:
| ------------------------------------------------------------------------------- |
| FIN PANEL/LOCATION DESIGNATION BUS ATA REF. |
| ------------------------------------------------------------------------------- |
| 7WD1 49VU A06 ENGINE/1/FIRE DET/LOOP A 401PP 26-12-00 |
| 8WD1 121VU Q38 ENGINE/ENG1/FIRE DET/LOOP B 202PP 26-12-00 |
| 7WD2 121VU Q39 ENGINE/ENG2/FIRE DET/LOOP A 202PP 26-12-00 |
| 8WD2 49VU A07 ENGINE/2/FIRE DET/LOOP B 401PP 26-12-00 |
| ------------------------------------------------------------------------------- |
5. Interface
The engine fire detection system has an interface with the following systems:
** ON A/C NOT FOR ALL The engine fire detection system has an interface with the following systems:
- Electrical Power: DC Ancillary Equipment (Ref. 24-68-00),
- Centralized Fault Display Interface Unit (CFDIU) (Ref. AMM D/O 31-32-00-00),
- Flight Warning Computer (FWC) (Ref. AMM D/O 31-52-00-00),
- Landing Gear Control and Interface Unit (LGCIU) (Ref. AMM D/O 32-31-00-00),
- Annunciator Light Test and Dimming (Ref. AMM D/O 33-14-00-00),
- Functional Interfaces (Ref. AMM D/O 73-25-00-00).
6. Component Description
The components of the fire detection system are for one engine:
The components of the fire detection system are for one engine:
- an ENG/APU FIRE panel on the overhead panel with:
. one ENG FIRE pushbutton switch,
. one TEST pushbutton switch, - two fire detection loops installed in parallel in the fire zones and connected to a Fire Detection Unit (FDU).
Each fire detection loop comprises three detectors connected in parallel. - one FDU per engine, which processes signals from the detectors
(1) ENG 1(2) FIRE pushbutton switch
The ENG 1(2) FIRE pushbutton switch can be pushed only if the safety guard is open.
Each pushbutton switch has three main functions:
The ENG 1(2) FIRE pushbutton switch can be pushed only if the safety guard is open.
Each pushbutton switch has three main functions:
- indicate the FIRE warning generated by the Fire Detection Unit,
- activate the microswitches involved in the extinguishing procedure, and
- arm the discharge function for bottles 1 and 2.
NOTE: For the last two functions, see ATA chapter 26-21-00.
(2) TEST pushbutton switch
The TEST pushbutton switch (one per engine) checks the condition of the:
The TEST pushbutton switch (one per engine) checks the condition of the:
- fire detectors (Loops A and B), Fire Detection Unit (FDU), indications, warnings and associated wirings (loop test),
- percussion cartridge filaments of the fire extinguisher bottles and associated wiring (squib test).
B. Fire Detectors
Each fire and overheat detector has a sensing element and responder assembly.
Each fire and overheat detector has a sensing element and responder assembly.
(1) Sensing element
A sensing element is a tube 0.063 in. (1.6 mm) in outer diameter and 0.018 in. (0.46 mm) in thickness.
It contains a hydrogen-charged titanium core with a spiral wound around it. This spiral is made of an inert material which has a special property: it can give off and absorb a gas.
The gap between the sensing-element outer-tube wall and the core is filled with helium.
The initial pressure of the helium is related to the pre-set temperature threshold selected for each sensing element.
The sensing element reacts according to the ideal gas law.
One end of the sensing element is hermetically soldered and the other one is connected to a 1 in. (25.4 mm) diameter stainless steel body called responder.
A sensing element is a tube 0.063 in. (1.6 mm) in outer diameter and 0.018 in. (0.46 mm) in thickness.
It contains a hydrogen-charged titanium core with a spiral wound around it. This spiral is made of an inert material which has a special property: it can give off and absorb a gas.
The gap between the sensing-element outer-tube wall and the core is filled with helium.
The initial pressure of the helium is related to the pre-set temperature threshold selected for each sensing element.
The sensing element reacts according to the ideal gas law.
One end of the sensing element is hermetically soldered and the other one is connected to a 1 in. (25.4 mm) diameter stainless steel body called responder.
(2) Responder assembly
The responder contains a chamber connected to two pressure switches :
an ALARM switch and a MONITOR switch. The free end of the responder is connected to the aircraft electrical circuit.
The detector has two sensing functions. It responds to an overall "average" temperature threshold or to a highly localized "discrete" temperature caused by impinging flame or hot gases. This results in the ALARM switch closure. the "average" and discrete temperatures cannot be adjusted.
In addition, the averaging and discrete functions are reversible.
When the sensor tube has cooled, the average gas pressure decreases and the core material absorbs the discrete hydrogen gas.
If the detector leaks, the gas pressure decrease causes the MONITOR switch to open and generates a detector fault signal.
The system then does not operate during test.
The responder contains a chamber connected to two pressure switches :
an ALARM switch and a MONITOR switch. The free end of the responder is connected to the aircraft electrical circuit.
The detector has two sensing functions. It responds to an overall "average" temperature threshold or to a highly localized "discrete" temperature caused by impinging flame or hot gases. This results in the ALARM switch closure. the "average" and discrete temperatures cannot be adjusted.
In addition, the averaging and discrete functions are reversible.
When the sensor tube has cooled, the average gas pressure decreases and the core material absorbs the discrete hydrogen gas.
If the detector leaks, the gas pressure decrease causes the MONITOR switch to open and generates a detector fault signal.
The system then does not operate during test.
(3) Location
The fire detection loop has three fire detectors connected in parallel. They are installed at the engine-to-pylon forward mount, in the fan compartment close to the accessories gearbox and vertically in the aft part of the core compartment.
The fire detection loop has three fire detectors connected in parallel. They are installed at the engine-to-pylon forward mount, in the fan compartment close to the accessories gearbox and vertically in the aft part of the core compartment.
(4) Location
The fire detection loop has three fire detectors connected in parallel. They are installed at the engine-to-pylon forward mount, in the fan compartment close to the accessories gearbox and horizontally in the aft part of the core compartment.
The fire detection loop has three fire detectors connected in parallel. They are installed at the engine-to-pylon forward mount, in the fan compartment close to the accessories gearbox and horizontally in the aft part of the core compartment.
(5) Installation
The fire detectors are installed in pairs on pre-formed, stainless steel supports on the engine (loop A and loop B).
The sensing elements are installed with quick-release clamps which have teflon bushings and are designed for continuous high temperature operation.
Temperature Chart:
The fire detectors are installed in pairs on pre-formed, stainless steel supports on the engine (loop A and loop B).
The sensing elements are installed with quick-release clamps which have teflon bushings and are designed for continuous high temperature operation.
Temperature Chart:
| ------------------------------------------------------------------------------ |
| Compartment Discrete Temperature Average Temperature |
| ------------------------------------------------------------------------------ |
| FAN 500 deg.C (932 deg.F) 221 deg.C (430 deg.F) |
| CORE 565 deg.C (1050 deg.F) 302 deg.C (575 deg.F) |
| PYLON 675 deg.C (1247 deg.F) 400 deg.C (752 deg.F) |
(6) Installation
The fire detectors are installed in pairs on pre-formed, stainless steel supports on the engine.
The sensing elements are installed with quick-release clamps which have teflon bushings and are designed for continuous high temperature operation.
Temperature Chart:
The fire detectors are installed in pairs on pre-formed, stainless steel supports on the engine.
The sensing elements are installed with quick-release clamps which have teflon bushings and are designed for continuous high temperature operation.
Temperature Chart:
| ------------------------------------------------------------------------------ |
| Compartment Discrete Temperature Average Temperature |
| ------------------------------------------------------------------------------ |
| FAN 538 deg.C (1000 deg.F) 235 deg.C (455 deg.F) |
| CORE 650 deg.C (1202 deg.F) 425 deg.C (797 deg.F) |
| PYLON 675 deg.C (1247 deg.F) 400 deg.C (752 deg.F) |
(7) Installation
The fire detectors are installed in pairs on pre-formed, stainless steel supports on the engine.
The sensing elements are installed with quick-release clamps which have teflon bushings and are designed for continuous high temperature operation.
Temperature Chart:
The fire detectors are installed in pairs on pre-formed, stainless steel supports on the engine.
The sensing elements are installed with quick-release clamps which have teflon bushings and are designed for continuous high temperature operation.
Temperature Chart:
| ------------------------------------------------------------------------------ |
| Compartment Discrete Temperature Average Temperature |
| ------------------------------------------------------------------------------ |
| FAN 500 deg.C (932 deg.F) 221 deg.C (430 deg.F) |
| CORE 621 deg.C (1150 deg.F) 375 deg.C (707 deg.F) |
| PYLON 675 deg.C (1247 deg.F) 400 deg.C (752 deg.F) |
C. Fire Detection Unit
The Fire Detection Unit (FDU) processes the signals received from the fire detection loops.
There are three functional modules:
The Fire Detection Unit (FDU) processes the signals received from the fire detection loops.
There are three functional modules:
- two independent channels (1 for each detection loop)
- one monitoring circuitry (for maintenance purpose only).
(1) The channels
Each channel has its own power supply.
The two channels normally operate together, with an AND logic, for the fire detection. However, if one loop is inoperative, the other loop can operate independently.
Each channel has its own power supply.
The two channels normally operate together, with an AND logic, for the fire detection. However, if one loop is inoperative, the other loop can operate independently.
(a) Input signals
Each channel receives and analyzes continuously the signal from its related detection loop. Three comparators are used for this analysis:
Each channel receives and analyzes continuously the signal from its related detection loop. Three comparators are used for this analysis:
- the FIRE comparator
- the CONTAMINATION comparator
- the INTEGRITY comparator
(b) Output signals
The output signals are generated via discrete signals and/or the ARINC 429 bus. The fire warning signals (aural and/or visual) thus generated are transmitted to the cockpit.
The output signals are generated via discrete signals and/or the ARINC 429 bus. The fire warning signals (aural and/or visual) thus generated are transmitted to the cockpit.
(2) Monitoring circuitry
The monitoring circuitry analyses and monitors continuously the fire detection system.
In case of failure of the system the monitoring circuitry:
The monitoring circuitry analyses and monitors continuously the fire detection system.
In case of failure of the system the monitoring circuitry:
- memorizes the fault in a non-volatile memory,
- isolates the faulty channel,
- generates the appropriate discrete signals,
(i.e. LOOP A(B) INOP ENG 1 (2) to the FWC 1(2)) - transmits continuously a system status message to the CFDIU 1(2) via the ARINC 429 bus.
7. Operation/Control and Indicating
(1) Operation of the channels
Channels A and B are identical and particular to each fire detection loop.
The input section of each channel comprises a bridge circuit with:
The reference voltage is sent to the three comparators (FIRE, INTEGRITY and CONTAMINATION) and forms the thresholds values. A resistor, upstream of each comparator, adjusts this reference voltage which becomes the comparator threshold value.
Each fire detector resistance is 4.5 Kohms, thus the equivalent resistance of each fire detection loop is 1.5 Kohms.
The equivalent resistance varies when a change of state occurs in the monitored areas of the engine. This generates a variable loop voltage at the three comparators.
The comparator outputs are sent on the FIRE and FAULT logic gates. The logic gates generate the alarm outputs.
Channels A and B are identical and particular to each fire detection loop.
The input section of each channel comprises a bridge circuit with:
- a reference voltage,
- a variable loop voltage made of the three fire detectors in parallel.
The reference voltage is sent to the three comparators (FIRE, INTEGRITY and CONTAMINATION) and forms the thresholds values. A resistor, upstream of each comparator, adjusts this reference voltage which becomes the comparator threshold value.
Each fire detector resistance is 4.5 Kohms, thus the equivalent resistance of each fire detection loop is 1.5 Kohms.
The equivalent resistance varies when a change of state occurs in the monitored areas of the engine. This generates a variable loop voltage at the three comparators.
The comparator outputs are sent on the FIRE and FAULT logic gates. The logic gates generate the alarm outputs.
(a) Normal conditions
In normal conditions (no failure, no fire, no test), the variable voltage of the loop is:
In normal conditions (no failure, no fire, no test), the variable voltage of the loop is:
- higher than the threshold 1 of the integrity comparator
- lower than the threshold 2 of the fire and contamination thresholds.
1 INTEGRITY Fault
Any failure of the fire detector (responder/sensing element) causes an increase of the equivalent resistance of the three other fire detectors.
A detector can be unserviceable because of:
. the opening of a MONITOR switch installed in series with an integral resistance,
. or the loss of the electrical signal. The loop voltage decreases and falls under the threshold 1 of the INTEGRITY comparator: this generates a LOOP A(B) INOP signal.
This failure description is also applicable in case of accidental grounding of the responder.
Any failure of the fire detector (responder/sensing element) causes an increase of the equivalent resistance of the three other fire detectors.
A detector can be unserviceable because of:
. the opening of a MONITOR switch installed in series with an integral resistance,
. or the loss of the electrical signal. The loop voltage decreases and falls under the threshold 1 of the INTEGRITY comparator: this generates a LOOP A(B) INOP signal.
This failure description is also applicable in case of accidental grounding of the responder.
2 CONTAMINATION Fault
If the responder or the connectors of FDU are contaminated:
. the equivalent resistance decreases
. the loop voltage is higher than threshold 2 and lower than 3
. the CONTAMINATION comparator supplies the logic gates and generates a FAULT signal.
If the responder or the connectors of FDU are contaminated:
. the equivalent resistance decreases
. the loop voltage is higher than threshold 2 and lower than 3
. the CONTAMINATION comparator supplies the logic gates and generates a FAULT signal.
(c) FIRE circuit
The detection of a fire by one of the responders causes the closure of the corresponding ALARM switch.
This generates a voltage higher than the threshold of the INTEGRITY and CONTAMINATION comparators. The FIRE comparator supplies the logic gates and transmits a FIRE signal.
The detection of a fire by one of the responders causes the closure of the corresponding ALARM switch.
This generates a voltage higher than the threshold of the INTEGRITY and CONTAMINATION comparators. The FIRE comparator supplies the logic gates and transmits a FIRE signal.
(2) Controller circuit
The controller circuit operating software:
The controller circuit operating software:
- monitors the two detection loops,
- isolates the failed detector and loop circuit and memorizes the failures in a non-volatile memory,
- does a check of the fire test circuity when it is activated,
- does the self-test at the first power-up of the FDU,
- does the built-in test and transmits the test results on the ARINC 429 bus,
- transmits the failure signals to the CFDIU via the ARINC 429 bus,
- continuously transmits current and/or previous system status on the ARINC 429 bus,
- provides a serial bus interface and does command and data transmissions.
(3) Indicating
(a) FAULT Warnings
FAULT warnings are generated via discrete signals.
FAULT warnings are generated via discrete signals.
1 There is an INOP signal if any of the following conditions occurs:
- an electrical failure (loss of power, connector not connected)
- a failure in a detector
- a failure in a detection circuit
- the detection of a single fire detection loop for a time greater than 16 sec while the other loop is in normal condition.
2 The FAULT warning signals thus generated are transmitted to the cockpit, at the following locations:
- MASTER CAUT light
- Upper ECAM display unit: ENG 1 (2) LOOP A (B) FAULT or ENG 1 (2) DET FAULT.
NOTE: In addition, the failure message in plain language is transmitted continuously via the ARINC 429 bus to the CFDIU.
(b) FIRE Warnings
FIRE warnings are generated via discrete signals.
FIRE warnings are generated via discrete signals.
1 There is a FIRE warning signal if any of the following conditions occurs:
- FIRE A and FIRE B
- FIRE A and FAULT B
- FAULT A and FIRE B
- FAULT A and FAULT B in less than 5 seconds.
2 The FIRE warning signals thus generated are transmitted to the cockpit, at the following locations:
- ENG/APU FIRE panel (1WD): ENG/FIRE pushbutton switch
- ENG panel (115VU): ENG/FIRE/FAULT annunciator
- MASTER WARN light
- Upper ECAM display unit: ENG 1 (2) FIRE and fire extinguishing procedure
- Lower ECAM display unit: engine page.
8. BITE Test
A. Operational Test
The operational test enables the pilot to monitor and activate the fire protection system. This test is part of the daily check-list and is available each time it is needed.
The operational test can be performed on the ground or in flight.
From the ENG/APU FIRE panel, a TEST pushbutton switch (one per engine) checks the condition of the:
When you press the TEST pushbutton switch, the fire warning indications are triggered, the fire detection system is operational.
For the engine 1 (same for the engine 2):
If the failure is detected during the TEST sequence, a FAULT message comes into view in the lower ECAM DU (For example ENG 1 (2) LOOP A(B) FAULT).
The operational test enables the pilot to monitor and activate the fire protection system. This test is part of the daily check-list and is available each time it is needed.
The operational test can be performed on the ground or in flight.
From the ENG/APU FIRE panel, a TEST pushbutton switch (one per engine) checks the condition of the:
- fire detectors (Loops A and B), Fire Detection Unit (FDU), indications, warnings and associated wirings (loop test)
- percussion cartridge filaments of the fire extinguisher bottles and associated wiring (squib test).
When you press the TEST pushbutton switch, the fire warning indications are triggered, the fire detection system is operational.
For the engine 1 (same for the engine 2):
- on the ENG/APU FIRE panel (1WD):
. the ENG 1 FIRE legend comes on,
. the SQUIB and DISCH legends come on, - on the ENG panel (115VU):
. the FIRE legend comes on, - on the panels 130VU and 131VU:
. the MASTER WARN lights flash, - on the upper ECAM display unit:
. the red ENG 1 FIRE indication comes into view, - on the lower ECAM display unit:
. the ENGINE page comes into view, - the Continuous Repetitive Chime (CRC) sounds.
If the failure is detected during the TEST sequence, a FAULT message comes into view in the lower ECAM DU (For example ENG 1 (2) LOOP A(B) FAULT).
NOTE: The TEST pushbutton switch must be held while you do the test.
B. Built-In Test Equipment (BITE)
(1) Description
The function of the BITE is to:
The FDU is a type 2 system. The FDU BITE functions are as follows:
The BITE test of the FDU is performed at power up or when the maintenance test discrete signal is sent from the MCDU via the CFDIU. In the two cases, the BITE test is performed if and only if the aircraft is on the ground.
Upon selection by the operator from the MCDU, the CFDIU displays the
"FIRE PROT: FDU 1 (2)" menu and presents data on the MCDU.
For the system, the basic functions are:
BITE Test duration:
During a system test, all the detectors are isolated from the FDU. The detector conditions are simulated by the BITE to test any failure in the FDU and its connections.
The BITE can tell if the failure is in the detector or the circuitry.
The function of the BITE is to:
- monitor the condition of the FDU and the related inputs,
- analyze and confirm the faults and,
- store them in the Non-Volatile Memory (NVM).
The FDU is a type 2 system. The FDU BITE functions are as follows:
- acquisition of discrete input signals,
- link with the CFDS (thru an ARINC 429 bus),
- memorization of failure in a NVM,
- tests.
The BITE test of the FDU is performed at power up or when the maintenance test discrete signal is sent from the MCDU via the CFDIU. In the two cases, the BITE test is performed if and only if the aircraft is on the ground.
Upon selection by the operator from the MCDU, the CFDIU displays the
"FIRE PROT: FDU 1 (2)" menu and presents data on the MCDU.
For the system, the basic functions are:
- LAST LEG/GND REPORT,
- PREVIOUS LEGS REPORT,
- LRU IDENTIFICATION,
- TROUBLE SHOOTING DATA,
- CLASS 3 FAULTS,
- TEST.
BITE Test duration:
- at power up: 60 s,
- at the maintenance test: 60 s.
During a system test, all the detectors are isolated from the FDU. The detector conditions are simulated by the BITE to test any failure in the FDU and its connections.
The BITE can tell if the failure is in the detector or the circuitry.
(2) Test combinations used by the BITE are as follows:
- Loop A NORMAL and Loop B NORMAL
- Loop A FIRE and Loop B FIRE
- Loop A INTEGRITY FAULT and Loop B FIRE
- Loop A NORMAL and Loop B NORMAL
- Loop A FIRE and Loop B INTEGRITY FAULT
- Loop A FIRE for less than 17 seconds while Loop B is NORMAL
- Loop A FIRE for more than 17 seconds while Loop B is NORMAL
- Loop B FIRE for less than 17 seconds while Loop A is NORMAL
- Loop B FIRE for more than 17 seconds while Loop A is NORMAL
- Loop A NORMAL and Loop B NORMAL
- Loop A CONTAMINATION FAULT and then Loop B CONTAMINATION FAULT within 5 seconds
(3) The list of maintenance messages sent to the CFDIU by the FDU is as follows:
| ------------------------------------------------------------------------------- |
| MAINTENANCE MESSAGES CLASS INT/EXT ATA REF |
| ------------------------------------------------------------------------------- |
| CHECK ENG (*) FIRE LOOP A 1 INT 26-12-15 |
| CHECK ENG (*) FIRE LOOP B 1 INT 26-12-15 |
| CHECK FDU ENG (*) SUPPLY 1 INT 26-12-00 |
| CHECK FDU ENG (*) LOOP A WARN CKT 3 INT 26-12-00 |
| CHECK FDU ENG (*) LOOP B WARN CKT 3 INT 26-12-00 |
| CHECK FDU ENG (*) FIRE A WARN CKT 3 INT 26-12-00 |
| CHECK FDU ENG (*) FIRE B WARN CKT 3 INT 26-12-00 |
| CHECK FDU ENG (*) LGCIU INTFC 3 EXT 26-12-00 |
| CHECK FDU ENG (*) PIN PROG 3 INT 26-12-00 |
| CHECK FDU PIN PROG 3 INT 26-10-00 |
| FDU ENG (*) 3 INT 26-12-34 |
| ------------------------------------------------------------------------------- |
| * = 1 (2) for engine 1 (2) |
NOTE: When the failure occurs on the ground, GND precedes the maintenance message.
(4) Description
The function of the BITE is to:
The FDU is a type 2 system. The FDU BITE functions are as follows:
The BITE test of the FDU is performed at power up or when the maintenance test discrete signal is sent from the MCDU via the CFDIU. In the two cases, the BITE test is performed if and only if the aircraft is on the ground.
Upon selection by the operator from the MCDU, the CFDIU displays the
"FIRE PROT: FDU 1 (2)" menu and presents data on the MCDU.
For the system, the basic functions are:
BITE Test duration:
During a system test, all the detectors are isolated from the FDU. The detector conditions are simulated by the BITE to test any failure in the FDU and its connections.
The BITE can tell if the failure is in the detector or the circuitry.
The function of the BITE is to:
- monitor the condition of the FDU and the related inputs,
- analyze and confirm the faults and,
- store them in the Non-Volatile Memory (NVM).
The FDU is a type 2 system. The FDU BITE functions are as follows:
- acquisition of discrete input signals,
- link with the CFDS (thru an ARINC 429 bus),
- memorization of failure in a NVM,
- tests.
The BITE test of the FDU is performed at power up or when the maintenance test discrete signal is sent from the MCDU via the CFDIU. In the two cases, the BITE test is performed if and only if the aircraft is on the ground.
Upon selection by the operator from the MCDU, the CFDIU displays the
"FIRE PROT: FDU 1 (2)" menu and presents data on the MCDU.
For the system, the basic functions are:
- LAST LEG/GND REPORT,
- LRU IDENTIFICATION,
- CLASS 3 FAULTS,
- TEST.
BITE Test duration:
- at power up: 75 s,
- at the maintenance test: 90 s.
During a system test, all the detectors are isolated from the FDU. The detector conditions are simulated by the BITE to test any failure in the FDU and its connections.
The BITE can tell if the failure is in the detector or the circuitry.
(5) Test combinations used by the BITE are as follows:
(a) Check:
- loops A and B for normal operating condition,
- the initial conditions to start the test.
(b) Simulate FIRE on loops A and B (Simulate normal condition).
(c) CONTAMINATION FAULT A, then simulate FIRE B (Simulate normal condition).
(d) CONTAMINATION FAULT B, then simulate FIRE A (Simulate normal condition).
(e) Check loops A and B for normal condition.
(f) Simulate normal FIRE A and B. After 26 seconds, when A is faulty, simulate contamination fault B (Simulate normal condition).
(g) Check loops A and B for normal condition.
(h) Simulate normal FIRE B and A. After 26 seconds, when B is faulty, simulate contamination fault A (Simulate normal condition).
(i) Check loops A and B for normal condition.
(j) Simulate INTEGRITY FAULT on loop A then on B, 4 seconds later and check power supplies, filaments and low pressure contacts of fire extinguisher bottles (Simulate normal condition).
(k) Simulate CONTAMINATION FAULT on loop A and CONTAMINATION FAULT on loop B 6 seconds later. Simulate normal condition.
(l) END OF TEST. Check loops A and B for normal condition.
(6) The list of maintenance messages sent to the CFDIU by the FDU is as follows:
| ------------------------------------------------------------------------------- |
| MAINTENANCE MESSAGES CLASS INT/EXT ATA REF |
| ------------------------------------------------------------------------------- |
| CHECK ENG (*) FIRE LOOP A 1 INT 26-12-15 |
| CHECK ENG (*) FIRE LOOP B 1 INT 26-12-15 |
| CHECK FDU ENG (*) CHAN B SUPPLY 1 INT 26-12-00 |
| CHECK FDU ENG (*) LOOP A WARN CKT 1 INT 26-12-00 |
| CHECK FDU ENG (*) LOOP B WARN CKT 1 INT 26-12-00 |
| CHECK FDU ENG (*) FIRE A WARN CKT 1 INT 26-12-00 |
| CHECK FDU ENG (*) FIRE B WARN CKT 1 INT 26-12-00 |
| CHECK FDU ENG (*) LGCIU INTFC 3 EXT 26-12-00 |
| CHECK FDU ENG (*) PIN PROG 3 INT 26-12-00 |
| CHECK FDU PIN PROG 3 INT 26-10-00 |
| FDU ENG (*) 1 INT 26-12-34 |
| POWER SUPPLY INTERRUPT 1 EXT 24-00-00 |
| CHECK CFDIU/FDU ENG (*) INTFC 3 EXT 31-32-34 |
| CHECK ENG (*) FIRE LOOP A + LOOP B 1 EXT 26-12-15 |
| CHECK FDU ENG (*) FIRE TEST 1 EXT 26-12-00 |
| PB SW/FDU ENG (*) |
| ------------------------------------------------------------------------------- |
| * = 1 (2) for engine 1 (2) |
NOTE: When the failure occurs on the ground, GND precedes the maintenance message.
(7) FDU Power-up Test
(a) Conditions of Power-up Test Initialisation
1 Necessary Computer de-energization Time:
- 200 ms.
2 A/C configuration:
- whatever the A/C configuration on the ground.
(b) Progress of Power-up Test
1 Duration:
- 5 sec.
2 Cockpit repercussions directly linked to power-up test accomplishment (some other repercussions may occur depending on the A/C configuration but these can be disregarded):
- ENG 1 (2)/APU FIRE panel:
. FIRE handle is flashing four times.
(c) Results of Power-up Test
1 Test passed:
- no message.
2 Test failed:
- MASTER CAUT ON with single chime,
- ECAM warning:
. ENG 1 (2) (APU) FIRE DET FAULT - ECAM STATUS page:
. FIRE DET 1 (2) (APU) INOP